Allow iterating over the frames of a CapturedJSStack

[simonwuelker]

This adds CapturedJSStack::for_each_stack_frame which calls the provided closure for each element in the linked list of SavedFrames. Unfortunately, I don't think there's an easy way to make this an iterator over SavedFrames, because of the lifetime associated with a RootedGuard.

for_each_stack_frame is useful for providing js backtraces in functions like console.trace.

[jdm]

Nice!

[jdm]

Could you add a test in https://github.com/servo/mozjs/blob/main/mozjs/tests/capture_stack.rs ?

[simonwuelker]

Could you add a test in https://github.com/servo/mozjs/blob/main/mozjs/tests/capture_stack.rs ?

Done. Should I create a new release for mozjs or is it fine to pin the git commit in servo?

[simonwuelker]

Ugh, the test passes individually but the other tests are interfering with the engine initialization (because the engine is global state).

Fixed by moving the test into its own file.

[jdm]

Could you add a test in https://github.com/servo/mozjs/blob/main/mozjs/tests/capture_stack.rs ?

Done. Should I create a new release for mozjs or is it fine to pin the git commit in servo?

Since this PR only modifies Rust code, we can just update the git revision. C++ changes need a version number update to ensure new static library binaries are published.